Linux From Scratch - Version 6.8

Chapter 7. Setting Up System Bootscripts

7.8. The
Bash Shell Startup Files

The shell program /bin/bash (hereafter referred to as
“the shell”) uses a collection
of startup files to help create an environment to run in. Each file
has a specific use and may affect login and interactive environments
differently. The files in the /etc
directory provide global settings. If an equivalent file exists in
the home directory, it may override the global settings.

An interactive login shell is started after a successful login, using
/bin/login, by reading
the /etc/passwd file. An interactive
non-login shell is started at the command-line (e.g., [prompt]$/bin/bash). A non-interactive shell
is usually present when a shell script is running. It is
non-interactive because it is processing a script and not waiting for
user input between commands.

For more information, see info
bash under the Bash
Startup Files and Interactive Shells section.

The files /etc/profile and ~/.bash_profile are read when the shell is invoked
as an interactive login shell.

Correct classification of characters into letters, digits and
other classes. This is necessary for bash to properly accept
non-ASCII characters in command lines in non-English locales

The correct alphabetical sorting order for the country

Appropriate default paper size

Correct formatting of monetary, time, and date values

Replace <ll> below
with the two-letter code for the desired language (e.g.,
“en”) and <CC> with the two-letter code
for the appropriate country (e.g., “GB”). <charmap> should be replaced
with the canonical charmap for your chosen locale. Optional modifiers
such as “@euro” may also be
present.

The list of all locales supported by Glibc can be obtained by running
the following command:

locale -a

Charmaps can have a number of aliases, e.g., “ISO-8859-1” is also referred to as
“iso8859-1” and
“iso88591”. Some applications
cannot handle the various synonyms correctly (e.g., require that
“UTF-8” is written as
“UTF-8”, not
“utf8”), so it is safest in
most cases to choose the canonical name for a particular locale. To
determine the canonical name, run the following command, where
<locale name> is the
output given by locale
-a for your preferred locale (“en_GB.iso88591” in our example).

LC_ALL=<locale name> locale charmap

For the “en_GB.iso88591”
locale, the above command will print:

ISO-8859-1

This results in a final locale setting of “en_GB.ISO-8859-1”. It is important that the
locale found using the heuristic above is tested prior to it being
added to the Bash startup files:

The above commands should print the language name, the character
encoding used by the locale, the local currency, and the prefix to
dial before the telephone number in order to get into the country. If
any of the commands above fail with a message similar to the one
shown below, this means that your locale was either not installed in
Chapter 6 or is not supported by the default installation of Glibc.

locale: Cannot set LC_* to default locale: No such file or directory

If this happens, you should either install the desired locale using
the localedef command,
or consider choosing a different locale. Further instructions assume
that there are no such error messages from Glibc.

Some packages beyond LFS may also lack support for your chosen
locale. One example is the X library (part of the X Window System),
which outputs the following error message if the locale does not
exactly match one of the character map names in its internal files:

Warning: locale not supported by Xlib, locale set to C

In several cases Xlib expects that the character map will be listed
in uppercase notation with canonical dashes. For instance,
"ISO-8859-1" rather than "iso88591". It is also possible to find an
appropriate specification by removing the charmap part of the locale
specification. This can be checked by running the locale charmap command in both
locales. For example, one would have to change
"de_DE.ISO-8859-15@euro" to "de_DE@euro" in order to get this locale
recognized by Xlib.

Other packages can also function incorrectly (but may not necessarily
display any error messages) if the locale name does not meet their
expectations. In those cases, investigating how other Linux
distributions support your locale might provide some useful
information.

Once the proper locale settings have been determined, create the
/etc/profile file:

The “C” (default) and
“en_US” (the recommended one
for United States English users) locales are different.
“C” uses the US-ASCII 7-bit
character set, and treats bytes with the high bit set as invalid
characters. That's why, e.g., the ls command substitutes them with
question marks in that locale. Also, an attempt to send mail with
such characters from Mutt or Pine results in non-RFC-conforming
messages being sent (the charset in the outgoing mail is indicated as
“unknown 8-bit”). So you can
use the “C” locale only if you
are sure that you will never need 8-bit characters.